Drive connection for a shaver blade



Dec. 11, 1962 1 F WAHL 3,067,511

DRIVE CONNECTION FOR A SHAVER BLADE Filed MalCh 25, 1960 fifa, 1 I fil-a2 0\ E? Lmw YMMM/ United States Patent O 3,067,511 DRIVE CONNECTION FOR A SHAVER BLADE John F. Wahl, Sterling, Ill., assigner to Wahl Clipper Corporation, Sterling, Ill., a corporation of Illinois Filed Mar. 23, 1960, Ser. No. 17,073 2 Claims. (Cl. 30-43) This invention relates to a drive connection, and more particularly to a pivotal drive connection between the armature of a vibratory electric motor and the inner movable blade of an electric shaver.

In electric Shavers of the kind powered by vibratory electric motors, a drive linger is connected at one end to the vibrating armature and the other end is connected to the movable cutting blade. In the past, as exemplified by Wahl Patent No. 2,256,932, FIG. 3, the base of the inner movable blade was provided with a centrally disposed notch or goove. This notch was oliset from the free end of the armature so that the drive finger which was secured to the free end of the armature had to be bent several times so its opposite end could enter the notch or groove in the base of the movable inner blade and establish the drive connection.

In this prior art arrangement the drive linger had a tendency to jump out of the groove in the base of the inner movable blade during operation. In addition, because of the complex shape of the drive linger, the drive linger was somewhat difficult and expensive to form.

As will be understood, there must be a pivotal connection between the free end of the drive linger and the base of the movable cutting blade. This pivotal connection must be strong and durable to withstand the continual pivoting movement between the drive linger and the base of the inner movable cutting blade. Additionally, the pivotal connection must operate freely to avoid power loss due to friction. For economy of manufacture the connection must be simple and easy to assemble accurately.

What is needed therefore and comprises the principal object of this invention is a simple, economical, electrically insulated and durable low friction arrangement providing a pivotal connection between the movable inner cutting blade and the drive finger of an electric shaver.

Other objects, advantages and details of the invention will be apparent as the description proceeds, reference being had to the accompanying drawing wherein one form of the invention is shown. It is to be understood that the description and drawing are illustrative only and that the scope of the invention is to be measured by the appended claims.

In the drawing: e

FIG. 1 is a plan view of an electric shaver with the casing cover removed to show the general arrangement of parts.

FIG. 2 is an enlarged sectional View showing the drive connection of the invention.

FIG. 3 is an enlarged sectional view of the connection.

AFiG. 4 is a plan view of the top surface of a portion of an extension on the base of the inner movable cutting blade showing the spaced tine receiving slots formed therein.

FIG. 5 is a sectional view on line 5-5 of FIG. 3.

FIG. 6 is an end View of the inner movable cutting blade and its base.

FIG. 7 is a sectional view on line 7-7 of FIG. 6.

Referring now to FIG. l of the drawing, an electric shaver indicated generally by the reference numeral 10 includes a casing l2 in which a vibratory electromagnetic motor 14 is mounted. The motor includes a core 16 on which a coil 18 is mounted in a manner well lCC known in the art. A motor armature 20 is pivotally mounted at end 22 on armature bracket 17.

Electric shaver 10 further includes a fixed outer or shear blade 26, shown in dotted line, and a movable inner cutting blade 28. The left end of blade 28 engages a casing portion 29 which serves as a bearing for the blade. As best seen in FIGS. l, 6 and 7, inner blade 28 includes a cutting portion 30 formed from initially liat thin prehardened sheet metal. This sheet metal is curved to desired shape and mounted on an electrically insulating base portion 32 as described more fully in my copending patent application, Serial No. 797,097, liled March 4, 1959but it is to be understood that the principles of this invention may be applied to electric shavers having blades of other types.

As best seen in FIGS. 2, 3 and 7, base portion 32 in the illustrated embodiment has an extension 34 at one end. This extension is reduced in thickness compared with the thickness of the remainder of the base portion for reasons to become apparent below, and for the most part is gen erally rectangular in cross section with parallel and planar upper and lower surfaces 36 and 38. As will be apparent later, the invention can be applied to base portions which do not have an extension as such, or to members which in effect are abbreviated base portions.

In this embodiment, a pair of elongated, linerally spaced drive linger receiving slots or openings 4l) and 42 extend through extension 34 from the lower surface 38 to the upper surface 36, see FIGS. 3, 4 and 5. Alternatively, a single, drive linger receiving slot or opening could be used, if desired.

As shown, linger receiving slots or openings 40 and 42 extend completely through extension 34, but, as will be seen, the invention can be applied to base portions, with or without extensions, having appropriately shaped openings which extend only part way through the base portion.

Slots or openings 40 and 42 each have side surfaces 44 and 46 (FIG. 3) which taper upwardly toward each other. By way of example, surfaces 44 and 46 lie at an angle of about 92 degrees with lower surface 38 of extension 34. Thus, surfaces 44 and 46 deline an angle of about 4 degrees. The spacing between side surfaces 44 and 46 of slots 40 and 42 at upper surface 36 of extension 34 is substantially equal to the thickness of drive linger 25. Corners 48 and 50 between upper surface 36 and surfaces 44 and 46, respectively, constitute pivoting regions or edges for drive linger 25.

The above described tapered arrangement is desirable from the standpoint of economy because it is easy to form slots 40 and 42 with the speciliedconverging side surfaces 44 and 46. However, it will be appreciated that the side surfaces of the slots need not be tapered -to form pivoting regions therein, and the pivoting regions instead of being corners may be arcuate or have other suitable shape. Consequently under some circumstances it may be desirable to use differently shaped slots and differently shaped pivoting regions. As stated above, however, it is important for the spacing between the pivoting regions to be closely related to the thickness of the drive linger 25 Drive linger 25 consists of sheet metal and is designed to be formed economically by a single stamping operation. One end 52 of drive linger 25 is secured rigidly to free end 24 of armature Ztl by any suitable means as by rivets, see FIG. 2. Opposite end 54 of the illustrated drive linger is bifurcated, delining tines 56 and 58, see FIG. 5. Tines 56 and 58 are designed to penetrate slots or openings 4t? and 42 4to a point beyond pivoting regions or corners 48 and Sli so that the drive linger can establish a pivoting drive connection between armature 20 and base 32. This means, in the form shown, that tines 56 and 58 extend 3 thro-ugh slots 4i) and 42 to a point beyond the upper surface 3o of extension 34, see FIGS. 2 and 3.

As seen in FEiG. 5, outer edges 60 and 62 of the tines are convergent. In addition the outer end surfaces 64 and 66 of slots 40 and 42 converge at the same angle. This arrangement limits the penetration of the tines in the slots, and the tines are snugly received therein without interfering with the pivotal connection between drive finger 25 and the base 32. In addition, the arrangement enables drive finger 25 to support the adjacent end of base portion 32 of inner blade 28, the opposite end being supported by casing portion 29.

During shaver operation the tines of drive finger 25 pivot on the pivoting regions or corners 4S and Sti as inner movable cutting blade 23 is driven back and forth. This pivotal connection between drive finger 25 and base 32 is simple, strong and easy to assemble. in addition, the pivoting action is substantially friction free and is extremely quiet in operation.

From the above description it is thought that the construction and advantages of this invention will -be readily apparent to those skilled in .the art. Various changes in detail may be made without departing from the spirit or losing the advantages of the invention.

Having thus described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. In an electric shaver, a vibratory electromagnetic motor and an inner movable cutting blade, said motor including an armature mounted at one end lfor vibratory movement, an elongated drive finger formed from sheet metal, one end of said drive inger secured to the free end of said armature, said inner movable cutting blade including a cutting portion and an attached base portion, said base portion having an extension on one end, said extension reduced in thickness in comparison with the thickness of the remainder of said base portion and generally rectangular in cross section with parallel upper and lower surfaces and having elongated linerally spaced slots eX- tending therethrough communicating with said upper and lower surfaces to define drive iinger receiving openings, the side surfaces of said slots converging from the lower surface of said extension to the upper surface in such a Way that the separation ofthe side surfaces of said slots at the upper surface of said extension is substantially equal to the thickness of said drive finger, the upper surface of said extension joining the side surfaces of said slots to form pivot corners, the opposite end of said drive finger bifurcated with each tine penetrating one of said slots to a point beyond the upper surface of said extension whereby the drive finger can pivot on saidpivot corners, the outer edges of the tines converging `toward each other and the outer end surfaces of the slots converging at the same angle whereby the tines of said drive linger are received snugly in said slots without interference to the pivotal relationship between the `drive finger and the base portion of the inner movable cutting blade.

'2. ln an electric shaverV having a casing, a vibratory armature mounted within said casing and a cutting blade having a base portion adapted to be driven by said armature, one end region of said base portion supported by said casing, the other end region of said base portion having a drive finger receiving opening, `a drive iinger of sheet material secured to said armature and extending into said opening, the side walls of said opening converging from bottom to top of said base portion whereby opposed surfaces of said drive finger engage said -base portion only at top pivot regions, the edges of said drive finger within said opening converging from bottom to top and engaging correspondingly converging end walls of said opening whereby said drive iinger supports said other end of said base portion.

References Cited in the iile of this patent UNITED STATES PATENTS 2,184,757 Sarnotey Dec. 26, 1939 2,263,747 Stein Nov. 25, 1941 2,345,695 Andis Apr. 4, 1944 2,702,938 Jepson Mar. 1, 1955 2,787,053 Kleinman Apr. 2, 1957 2,859,513 Bylund Nov. 11, 1958 

